Improper Initialization in Linux kernel - CVE-2026-64327
Published: July 27, 2026
Vulnerability identifier: #VU139649
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-64327
CWE-ID: CWE-665
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to improper initialization in the f_fs functionfs endpoint file handling when processing early userspace ioctls before USB host connection. A local user can invoke FUNCTIONFS_DMABUF_ATTACH on an endpoint file before the host connects to cause a denial of service.
The issue occurs because endpoint direction checks can use an incorrect DMA direction before the endpoint files are fully initialized for connection state.
How to mitigate CVE-2026-64327
Install security update from vendor's repository.